Autosomal dominant polycystic kidney disease is a multisystem disorder characterized by multiple, bilateral renal cysts and is also associated with cysts in other organs, such as the liver, pancreas, and arachnoid membranes. Dermatomyosiltis is a disease which mainly involves the skin and muscles, although occasionally other organs are affected. In this report, a 56-year-old male patient with a four-year history of autosomal dominant polycystic kidney disease was presented. Renal failure was exacerbated by a coexisting dermato-polymyositis. Prednisone treatment with hemodialysis improved the situation. This is the first report renal failure in a patient with autosomal dominant polycystic kidney disease and dermato-polymyositis.